Within the framework of prior studies carried out in the field of electronic marking and, more particularly, the effort against loss (French patent filed under the number 93 15063) we have observed that the energy sources, of the battery type, available on the market, do not correspond in most cases to the need for the electronic circuits used.
Conventional energy sources of self-contained or portable equipment, batteries and accumulators, are far from having ideal characteristics for the supply of modern electronic circuits.
Their voltage varies greatly in the course of their lifetime and their undesirable characteristics are their limited capacity, their size, their weight, and their cost of installation.
Most of these drawbacks could be corrected with the help of carefully selected mountings, external to the battery (see for example the patents WO 94/00888, EP 0 457 569, or FR 2 672 713).
Another major difficulty encountered, essentially with batteries, resides in the control:
of the quantity of energy available at any moment, in a battery,
of the quantity of energy necessary to recharge it,
of the control and estimation of the total lifetime of this battery, as a function of the conditions of use (number of cycles of charging and discharging, temperature of use, large current draws, frequency of current draws . . . ).
This difficulty of controlling the operation of a battery, and of the quantity of energy available, has not always been resolved in a satisfactory manner, until now, and the solutions brought to this problem remain overall solutions, external to the battery (see for example the patents EP 0 644 642, WO 92/16979 or WO 96/08846).
The invention has for its object the integration of an intelligence, in the form of one or several chips within the interior itself of each of the generator cells or electrochemical couples which constitute a battery, to control, directly on each of the elements, the parameters of the latter and to compute permanently the condition of the instantaneous health of the battery.
The invention thus permits providing smart batteries thanks to which it will be possible to control the matrices of energy sources, and hence to create a better adaptation between the electronic means used and the size of the energy source which itself is associated in the framework of microsystems of a very small consumption.
It is however necessary to give the following particularities:
electric batteries, designed for a single use, and hence discardable, are qualified from primary generators in that the electrical energy that they produce is introduced therein one time for all, during their production, in a chemical form.
This is in contrast to secondary generators which are batteries, true reservoirs that can be refilled during each recharge, from an external electrical energy source.
As to the latter, one can speak in present day terms of accumulators or batteries. However, this latter term is improper because it designates in fact any assembly of several elements, no matter what the type of battery.
For the sake of clarity, in the text, we will use:
the term xe2x80x9cnon-rechargeable batteryxe2x80x9d to designate a battery made of primary cells that are not rechargeable,
the term xe2x80x9crechargeable batteryxe2x80x9d to designate a battery with secondary cells, which therefore are rechargeable,
the term xe2x80x9cbattery cellxe2x80x9d to designate an element (or electrochemical pair) rechargeable or not.
It is known that rechargeable and non-rechargeable batteries are constituted of several identical battery cells mounted at present in series but that they could be disposed also with certain precautions, in parallel. FIGS. 1 and 2 show respectively by way of example a mounting in series and in parallel of battery cells 10.
Whether rechargeable or non-rechargeable, with liquid or solid electrolyte, with a cathode that is polarizable or not, with oxygen or another gas, each battery cell is constituted of an anode, a cathode, an electrolyte, one or several separators, a casing permitting holding and protecting the assembly, and two external electrical connections.
There also exist other modifications of cells, with gas circulation, electrolyte circulation, sea water circulation, for example.
The invention seeks to provide a battery cell, rechargeable or not, comprising within the electrochemical couple, an electronic chip supplied by said generator, and adapted to fulfill various functions such as, by way of non-limiting example:
controlling the output voltage of the cell,
controlling the current passing through the cell,
monitoring one or several parameters such as the temperature or pH of the cell,
computing the input or output energies,
memorizing the results,
transmitting data toward a centralized processing system,
or quite simply providing a microsource of energy, rechargeable or not.
Certain of these uses are the object of prior patents (see for example the patents EP 0 350 235, WO 93/14612 or WO 95/12901) but, in all cases, the electronic parts are connected to the outside of the electrochemical couple constituting the cell, over conductors used to cause the electrical current to flow supplied by said electrochemical couple, toward the user circuit.
In the patent EP 0 644 642, the electronic circuit is generally positioned on a surface plate, in a space available between the interior of the housing and the electrochemical couple. It is also proposed to integrate this electronic circuit within the materials constituting the cell, but such a modified embodiment is not described. The connection of the chip is however provided only outside the electrochemical couple.
The present invention thus relates to a cell of a rechargeable or non-rechargeable battery, comprising an electrochemical couple constituted by two electrodes separated by an electrolyte, characterized in that it comprises an electronic circuit disposed within said electrochemical couple and electrically connected to the electrodes.
The generator according to the invention is further noteworthy in that:
at least one of the electrodes comprising a current collector, the electronic circuit is electrically connected to said collector,
the electronic circuit is fixed on a current collector,
the current collector is constituted by the metallic cladding of a printed circuit card on which is fixed the electronic circuit,
the metallic cladding constituting the current collector covers the upper surface of said card, except for a central surface adapted for positioning the electronic circuit,
the electric circuit having connecting terminals, openings are formed in the card at the points where said connection terminals will be located, the lower surface of the card carrying a metallized coating constituted by circuits independent from each other of which one is connected electrically to the cladding of the upper surface through an opening in the card,
the connections are connected to the segments of the metallized coating of the lower surface of the card by microballs,
the contacts are connected to the metallized coating surfaces of the lower surface of the plate by conductive wires,
the electrolyte comprising a separator, the electronic circuit is fixed to said separator.
A process for the production of a cell according to the invention is characterized in that:
there is used a printed circuit card whose upper surface carries a metallic cladding adapted to constitute a current collector, said cladding covering the upper surface of said card, except a central surface adapted for positioning the electronic circuit and whose lower surface carries a metallized cladding constituted by segments independent of each other, of which one is electrically connected to the cladding of the upper surface through an opening in the card,
an electronic circuit is used having connection contacts,
openings are formed in the card at the points where said connection contacts will be located,
the electronic circuit is secured to the printed circuit card,
the connection contacts are electrically connected to the segments of the cladding of the oversurface of the card,
the electronic circuit is coated with a protective molding,
the electrochemical couple of the cell is constituted on the card used as a support for the collector, by forming a first electrode by deposition of material on the upper surface of the card, then by positioning the electrolyte and the second electrode on said first electrode,
an electrical connection is formed between one of the lower cladding segments and the electrode,
the electrochemical is enclosed in a housing.
A second process for production of a cell according to the invention is characterized in that:
there is used a separator as the electrolyte,
an opening is cut in said separator,
an electronic circuit is positioned in the opening and the connection contacts are connected to current collectors,
a molding is carried out about said electronic circuit so as to ensure the protection and its securement to said separator,
the electrodes on opposite sides of the separator are made to be in contact with the current collectors,
the electrochemical couple is enclosed in a housing.
A third process for production of a cell according to the invention is characterized in that:
the electrochemical couple is produced by stacking elements constituting the first electrode with its collector, the electrode and the second electrode with its collector so as to leave an empty cavity, and by positioning in said cavity a portion of each of the collectors,
the electric circuit is introduced into the cavity,
the connection contacts are connected to said collectors by means of connections,
the cavity is filled with resin so as to constitute the protective molding of said component,
the electrochemical couple is enclosed in a housing.
The invention also provides a process for making a cell according to the invention, characterized in that the electronic circuit ensures a function of analysis of at least one parameter of the electrochemical couple and transmits this information to external control means.
The information is transmitted by a radio frequency modulation process superposed on the supply voltage through the connections of the electronic circuit to the electrodes of the electrochemical couple and the connections of the electrodes of the electrochemical couple to the terminals of the cell.
The electronic circuit can be of any type, it is for example constituted by a chip or by several active or passive components.